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9618 Computer Science Advanced Theory > Set 2 (Comms and Security) > Flashcards

Set 2 (Comms and Security) Flashcards

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1
Q

Define HTTP

A

hypertext transfer protocol

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2
Q

Define Segment (transport layer)

A

This is a unit of data (packet) associated with the transport layer protocols

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3
Q

Define FTP

A

File transfer protocol

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4
Q

Define SMTP

A

Simple mail transfer protocol

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5
Q

Define push protocol

A

Protocol used when sending emails, in which the client opens the connection to the server and keeps the connection active all the time, then uploads new email to the server

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6
Q

Define binary file

A

a file that doesn’t contain text only. The file is machine-readable but non human-readable

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7
Q

Define MIME

A

Multi purpose internet mail extension. A protocol that allows email attachments containing media files as well as text to be sent

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8
Q

Define pull protocol

A

used when receiving emails, in which the client periodically connects to a server, checks for and downloads new emails from a server and then closes the connection

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9
Q

Define Host to Host

A

a protocol used by TCP when communicating between two devices

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10
Q

Define host

A

A computer or device that can communicate with other computers or devices on a network

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11
Q

Define BitTorrent

A

Protocol used in peer-to-peer networks when sharing files between peers

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12
Q

Define Peer

A

A client who is part of a peer-to-peer network/file sharing community

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13
Q

Define metadata

A

a set of data that describes and gives information about other data

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14
Q

Define pieces

A

Splitting up of a file when using peer-to-peer file sharing

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15
Q

Define tracker

A

A central server that stores details of all other computers on the swarm

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16
Q

Define Seed

A

a peer that has downloaded a file (or pieces of a file) and has then made it available to other peers in the swarm

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17
Q

Define Swarm

A

Connected peers (clients) that share a torrent/tracker

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18
Q

Define leech

A

A peer with negative feedback from swarm

19
Q

Define lurker

A

user/client that downloads files but does not supply any new content to the community

20
Q

What are the 4 stages of the TCP/IP protocol

A

4) Application layer
3) Transport Layer
2) Internet (network) Layer
1) Link Network

(Sending going from 4 –> 1)

21
Q

The TCP/IP protocol suite has four layers. The application layer provides user services. What are some protocols

A
  • HTTP(S) : For sending and receiving web pages / hypertext documents
  • FTP : For sending and receiving files over network
  • SMTP : For sending/uploading email/push protocols
  • POP : For receiving/downloading emails/pull protocols
22
Q

Describe the purpose of asymmetric key cryptography

A
  • To provide better security by using two different keys / a public key and a private key
  • One of the keys is used to encrypt the message and the matching key is used to decrypt the message
23
Q

What are the benefits of quantum cryptography

A
  • Provides security based on laws of physics rather than mathematical algorithms so more secure
  • To protect the security of the data transmitted over fibre optic cables
  • Virtually unhackable
  • The performance of quantum cryptography is continuously improved, making it suitable for most valuable government/industrial secrets.
  • Longer keys can be used
24
Q

What are the drawbacks of quantum cryptography

A
  • Lacks many vital features such as digital signature, certified mail, etc.
  • High cost of purchasing / maintaining equipment required.
  • Currently only works over relatively short distances.
  • Error rates are relatively high as technology is still being developed.
  • Polarisation of light can change during transmission.
  • Allows criminals and terrorists to hide their communications.
25
Q

Explain the application layer in TCP/IP

A
  • Contains all the programs that exchange data such as web browsers or server software
  • This layer allows the application to access the services used in other layers and also define the protocols that any app uses to allow the exchange of data
26
Q

Define HTTP(S)

A
  • Hyper text transfer protocol; this is a protocol responsible for correct transfer of files that make up web pages on the world wide web
  • Used when eg fetching an HTML document from a web server
27
Q

Define SMTP

A

simple mail transfer protocol; this handles the sending of emails

28
Q

Define POP3/4

A

post office protocol; this handles the receiving of emails

29
Q

Define IMAP

A

internet message access protocol; this handles the receiving of emails

30
Q

Define DNS

A

domain name service; protocol used to find the IP address, for example, when sending emails

translating domain names into a specific IP address so that the initiating client can load the requested Internet resources

31
Q

Define FTP

A

file transfer protocol; this is a protocol used when transferring messages
and attachments

32
Q

Define RIP

A

routing information protocol; this is the protocol routers use to exchange routing information over an IP network

33
Q

Define SNMP

A

simple network management protocol; protocol used when exchanging network management information between network management and network devices (such as routers, servers and other network devices)

34
Q

Describe the Internet/network layer

A
  • The internet layer identifies the intended network and host. The common protocol is IP (internet protocol).
  • It transmits packets to the link / physical layer
  • It routes the packets independently through the optimum route
  • It addresses packets with their source and destination IP address
  • It then uses an IP address and port number to form a socket
35
Q

Describe the Ethernet protocols

A
  • Destination
  • Source
  • Ethernet Type / Length
  • Actual message
  • Frame Check
36
Q

Describe the transport layer

A
  • The transport layer regulates the network connections; this is where data is
    broken up into packets which are then sent to the internet/network layer (IP
    protocol).
  • It sequences the packets and adds a packet header
  • It sends the packets to the internet layer
  • it controls the flow of packets
  • it handles packet loss/corruption
37
Q

What is meant by a private key

A
  • Unpublished key never transmitted anywhere
  • It has a matching public key
  • It is used to decrypt data that was encrypted with its matching public key
38
Q

Describe the process of asymmetric encryption.

A
  • The message to be sent is encrypted using the recipient’s public key. // The message to be sent is encrypted using the sender’s private key.
  • The message is decrypted using the recipient’s private key. // The message is decrypted using the sender’s public key.
39
Q

Explain how a digital signature is used to verify a message when it is received

A
  • The message together with the digital signature is decrypted using the receiver’s private key
  • The digital signature received is decrypted with the sender’s public key to recover the message digested sent
  • The decrypted message received is hashed with the agreed hashing algorithm to reproduce the message digest of the message received
  • The two message digests are compared
  • If both digests are the same the message has not been altered
40
Q

Explain the process by which an organisation may acquire its digital certificate.

A
  • The organisation requests a certificate from a Certificate Authority (CA)
  • The organisation may send their public key to CA
  • The organisation gathers all the information required by the CA in order to obtain their certificate, which includes information to prove their identity
  • The CA verifies the organisation’s identity
  • The CA generates / issues the certificate including the organisation’s public key (and other information).
41
Q

Explain why protocols are needed

A
  • Protocols set a standard for communication
  • Protocols enable communication/compatibility between devices from different manufacturers/platforms
  • If two devices were sending messages to each other but using different protocols, they would not be able to communicate properly
42
Q

What are the reasons for using key cryptography.

A

To ensure the message is authentic // came from a trusted source

  • To ensure that only the intended receiver is able to understand the message
  • To ensure the message has not been altered during transmission
  • Non-repudiation, neither the sender or receiver can deny the transmission occurred
43
Q

Explain how the digital signature can be checked on receipt to ensure that the message has not been altered during transmission.

A
  • The message together with the digital signature is decrypted using the receiver’s private key
  • The digital signature received is decrypted with the sender’s public key to recover the message digest sent
44
Q
A

9618 Computer Science Advanced Theory (3 decks)

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